KR100714015B1 - Organic luminescence display device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting display device, comprising: a light emitting device formed between a first substrate and a second substrate and emitting predetermined light; A retarder for changing phase, a first polarizer disposed on the retardation plate and reflecting light in a specific polarization direction, and a second polarizer disposed on the first polarizer and transmitting light in a polarization direction opposite to the specific polarization direction . The absorption of the external light is minimized by the absorption type polarizer having the anti-reflection film, and the luminous efficiency is increased by changing the phase of the light that is not emitted to the outside in the process of emitting the emitted light.

Absorption polarizer, Reflective polarizer, Wire grid polarizer, Retardation plate, Anti-reflection film

Description

Organic luminescence display device

1 is a schematic cross-sectional view illustrating an example of a conventional passive matrix organic light emitting display device.

2 is a schematic cross-sectional view illustrating an example of a conventional active matrix organic light emitting display device.

3 is a cross-sectional view illustrating an organic light emitting diode display according to a first exemplary embodiment of the present invention.

4 is a cross-sectional view illustrating an organic light emitting diode display according to a second exemplary embodiment of the present invention.

5 is a cross-sectional view illustrating an organic light emitting diode display according to a third exemplary embodiment of the present invention.

6 is a cross-sectional view illustrating an organic light emitting diode display according to a fourth exemplary embodiment of the present invention.

7 and 8 are cross-sectional views illustrating an operation of an organic light emitting diode display according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10, 50, 110: insulated substrate 11, 58: anode electrode

20, 59: organic thin film layer 21: hole transport layer

22 organic light emitting layer 23 electron transport layer

30, 60: cathode electrode 40, 70, 130: encapsulation substrate

51: semiconductor layer 52: gate electrode

53: source electrode 54: drain electrode

55, 57: electrode 56: dielectric

120: light emitting element 140: phase difference plate

150: first polarizer 160: second polarizer

170: shield

The present invention relates to an organic light emitting display, and more particularly, to an organic light emitting display capable of minimizing reflection of external light and increasing luminous efficiency.

Organic luminescence display devices are the next generation display devices with self-luminous characteristics.They are characterized in terms of viewing angle, contrast, response speed and power consumption compared to liquid crystal display devices (LCDs). It has excellent characteristics and can be manufactured in light weight and thinness because no backlight is required.

In the organic light emitting diode display, a passive matrix method in which scan lines and signal lines intersect and forms pixels in a matrix form, and thin film transistors in which operation of each pixel serves as a switch. The active matrix method controlled by the TFT.

In the passive matrix method, each pixel is driven by sequentially driving the scan lines over time. In the active matrix method, each pixel is driven by using a storage capacitor. Therefore, since the active matrix method can obtain the same brightness with low current, it consumes less power than the passive matrix method and is advantageous for high definition and large size.

1 is a schematic cross-sectional view illustrating an example of a conventional passive matrix organic light emitting display device.

An anode electrode 11 is formed on the insulating substrate 10, and an organic thin film layer 20 is formed on the anode electrode 11. The organic thin film layer 20 may have a structure in which the hole transport layer 21, the organic emission layer 22, and the electron transport layer 23 are stacked, and further include a hole injection layer and an electron injection layer. In addition, a cathode electrode 30 is formed on the organic thin film layer 20 so as to intersect the anode electrode 11, and an encapsulation substrate 40 for protecting the organic light emitting display device configured as described above on the entire upper portion of the organic thin film layer 20. The sealant (not shown) is attached to the substrate 10.

2 is a schematic cross-sectional view for describing an example of a conventional active matrix organic light emitting display device.

The thin film transistor T including the semiconductor layer 51, the gate electrode 52, the source and drain electrodes 53 and 54 is formed on the insulating substrate 50. The storage capacitor C _ST having the stacked structure of the electrode 55, the dielectric 56, and the electrode 57 is connected to the source electrode 53 of the thin film transistor T, and the anode is connected to the drain electrodes 53 and 54. The light emitting device E having the structure in which the electrode 58, the organic thin film layer 59, and the cathode electrode 60 are stacked is connected. The encapsulation substrate 70 for protecting the organic light emitting display device configured as described above is adhered to the substrate 50 by a sealant (not shown).

In the organic light emitting diode display configured as described above, when a predetermined voltage is applied to the anode electrode and the cathode electrode, holes injected through the anode electrode and electrons injected through the cathode electrode are recombined in the light emitting layer, and the energy difference generated in the process To emit light.

Therefore, the organic light emitting diode display may be classified into a bottom emission type in which the emitted light proceeds downward and a top emission method in which the emitted light proceeds upward.

In the bottom emission method, since the emitted light is emitted toward the substrate on which the thin film transistor is formed, the wiring portion including the thin film transistor is excluded from the display area. In the top emission method, the emitted light is emitted toward the upper part of the thin film transistor. You can get it.

In an organic light emitting display, the contrast ratio is a luminance ratio at on / off, which indicates the degree to which an image can be clearly recognized. The luminance at off is determined by reflectance of an external light source. Is determined. Therefore, in order to increase the contrast ratio, it is important to reduce the reflectance of the external light source.

In order to reduce the reflection of the external light source, a λ / 4 retardation plate and a polarizing plate are formed on the surface of the substrate along which the emitted light travels (see Korean Patent Application No. 2000-60523 (October 14, 2000)) or the phase difference adjustment A technique for forming this possible circularly polarizing plate has been proposed.

In the case of using a polarizing plate for passing a specific wavelength, for example, only the horizontal wave, the horizontal wave passing through the polarizing plate does not pass through the polarizing plate because the phase is changed by the λ / 4 retardation plate after being reflected by the internal metal electrode. Therefore, since the phase difference is induced by the λ / 4 retardation plate and the incident external light is not emitted, the reflection of the external light is reduced.

However, the organic light emitting diode display configured as described above has a disadvantage that luminance is reduced to less than half because light emitted from the inside is blocked by about 50% by the polarizer. In order to compensate for the luminance, the intensity of the light emitted should be increased by about 2 times, in which case the power consumption increases.

An object of the present invention is to provide an organic light emitting display device which can minimize reflection of external light and increase the amount of light emitted therein.

An organic light emitting display device according to an aspect of the present invention for achieving the above object is formed between a first and a second substrate, the first and second substrate, the light emitting device for emitting a predetermined light, in the light emitting device A retardation plate disposed on the substrate in a path in which the emitted light propagates and changing a phase of incident light, a first polarizer disposed on the retardation plate and reflecting light in a specific polarization direction, on the first polarizer And a second polarizer disposed to transmit light in a polarization direction opposite to the specific polarization direction.

In addition, an organic light emitting display device according to another aspect of the present invention for achieving the above object is formed on a substrate, a light emitting element formed on the substrate and emitting a predetermined light, the entire upper surface including the light emitting element A protective film, a retardation plate formed on the protective film to change a phase of incident light, a first polarizer disposed on the retardation plate and reflecting light in a specific polarization direction, and disposed on the first polarizer and in the specific polarization direction And a second polarizer for transmitting light in an opposite polarization direction.

The retardation plate is configured to change the phase of the incident light by 45 °, the first polarizer is made of a reflective polarizer such as a wire grid polarizer, and the second polarizer is made of an iodine absorbing polarizer.

An anti-reflection film is formed on the second polarizer, and the anti-reflection film is formed of an anti-glare film or an anti-reflection film.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided to those skilled in the art to fully understand the present invention, and may be modified in various forms, and the scope of the present invention is limited to the embodiments described below. no.

3 to 5 are cross-sectional views illustrating an organic light emitting diode display according to an exemplary embodiment of the present invention.

A light emitting device 120 for emitting a predetermined light is formed on an insulating substrate 110 made of a transparent material such as glass, and an encapsulation substrate 130 made of a transparent material is formed on the light emitting device 120. ) To the insulating substrate 110. In addition, a phase difference plate 140 is disposed on the insulating substrate 110 or the encapsulation substrate 130 along the path of the light emitted from the light emitting element 120 to change the phase of incident light by a predetermined angle. The first polarizer 150 reflecting light in a specific polarization direction is disposed on the retardation plate 140, and the second polarizer transmitting light in a polarization direction opposite to the specific polarization direction on the first polarizer 150. 160 is disposed.

As the first embodiment of the present invention, when the light emitting device 120 is configured in the bottom emission method, as shown in FIG. 3, the retardation plate 140, the first polarizer 150 and the lower portion of the insulating substrate 110, The second polarizer 160 is disposed.

As a second embodiment of the present invention, when the light emitting device 120 is configured in a top emission method, as shown in FIG. 4, the retardation plate 140, the first polarizer 150, and the upper portion of the encapsulation substrate 130. The second polarizer 160 is disposed.

As a third embodiment of the present invention, when the light emitting device 120 is configured in a double-sided light emission method, as shown in FIG. ), The first polarizer 150 and the second polarizer 160 are disposed.

The light emitting device 120 is configured in a passive matrix method including a lower electrode, an organic thin film layer, and an upper electrode, or includes a lower electrode, an organic thin film layer, and an upper electrode, and a thin film transistor (TFT) in which an operation of each pixel serves as a switch. It can be configured in an active matrix manner controlled by. The lower electrode is an anode electrode, and is formed of a transparent electrode material such as ITO, IZO, ITZO, etc., and the organic thin film layer has a structure in which a hole transport layer, an organic light emitting layer, and an electron transport layer are stacked, or a hole injection layer and an electron transport layer formed in the hole transport layer. An electron injection layer formed on the may be further included. The upper electrode is a cathode electrode, and is formed of a transparent electrode material such as ITO, IZO, ITZO or the like, or a metal having a low work function such as Ca, Mg, Al, Ag, or the like.

The retardation plate 140 is configured of, for example, a λ / 4 retardation plate capable of changing the phase of incident light by 45 °.

The first polarizer 150 is a reflective polarizer that reflects light in a specific polarization direction and transmits light in a polarization direction opposite to the specific polarization direction. The first polarizer 150 may be configured as a wire grid or the like. A wire grid polarizer having a fine period grating reflects parallel components and transmits vertical components when the period of the grating is shorter than the wavelength of incident light.

The second polarizer 160 is an absorption type polarizer that transmits light in a specific polarization direction and absorbs light that is not transmitted, and uses an iodine polarizer having excellent polarization degree. In addition, an anti-reflection film (not shown), such as an anti-glare film or an anti-reflection film, may be formed on the surface of the second polarizer 160 to minimize reflection of external light such as ultraviolet rays.

3 to 5 illustrate a structure in which the retardation plate 140, the first polarizer 150, and the second polarizer 160 are disposed on the insulating substrate 110 and the encapsulation substrate 130, but the insulating substrate ( The retardation plate 140, the first polarizer 150, and the second polarizer 160 may be disposed on the rear surface of the 110 and the encapsulation substrate 130.

6 is a cross-sectional view for describing an organic light emitting diode display according to a fourth exemplary embodiment of the present invention. Although FIG. 6 is structurally similar to the organic light emitting diode display illustrated in FIG. 4, AlxOy, The protective film 170 is formed of SiOxNy, SixNy, MgO, TixOy, BxOy, VxOy, AlTixOy, and the like, and the encapsulation substrate (130 of FIG. 4) is not formed and the retardation plate 140 and the first polarizer are formed on the protective film 170. 150 and second polarizer 160 are disposed.

7 and 8 are cross-sectional views for describing the operation of the organic light emitting diode display according to the present invention configured as described above.

When a predetermined voltage is applied to the lower electrode as the anode electrode and the upper electrode as the cathode electrode, the light emitting device 120 recombines holes injected through the lower electrode and electrons injected through the upper electrode in the organic emission layer. Light is emitted by the difference in energy generated by the. Meanwhile, while the light emitted from the light emitting element 120 is emitted to the outside, external light is incident on the organic light emitting diode display from an external light source.

Referring to FIG. 7, when external light is incident from the external light source through the second polarizer 160, the second polarizer 160 transmits, for example, vertical waves and absorbs horizontal waves in the external light. At this time, the reflection of external light is hardly generated by the anti-reflection film formed on the surface of the second polarizer 160.

For example, when the external light of the vertical wave passing through the second polarizer 160 passes through the first polarizer 150 and the retardation plate 140 and is incident therein, the phase is shifted by the phase difference plate 140, for example, 45. ° is changed. In addition, the external light of the vertical wave reflected by the internal metal electrode is changed by the phase difference plate 140 into a horizontal wave again by 45 °. The external light changed into the horizontal wave is reflected by the first polarizer 150, and the phase is changed by the retardation plate 140 to be 45 ° to become a vertical wave, and is emitted to the outside through the first polarizer 160. However, since the intensity of light emitted in this process is weakened and some light is reflected back to the first polarizer 150, most of the incident external light is extinguished and the reflection of external light is minimized.

Referring to FIG. 8, vertical waves of light emitted from the light emitting device 120 are emitted to the outside through the retardation plates 140, the first and second polarizers 150 and 160, and the horizontal waves are transmitted to the retardation plate 140. The phase changes by 45 °. The horizontal wave whose phase is changed is reflected by the first polarizer 150 and then is changed by 45 ° by the phase difference plate 140 to become a vertical wave, and is emitted to the outside through the second polarizer 160. Therefore, since the horizontal wave which is not emitted to the outside is changed by the phase difference plate 140 and the first polarizer 150 and then is emitted through the second polarizer 160, the amount of emitted light is increased compared with the related art.

As described above, the preferred embodiment of the present invention has been disclosed through the detailed description and the drawings. The terms are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, the present invention minimizes the reflection of external light by the absorption type polarizer having the anti-reflection film, and the light that is not emitted to the outside in the process of emitting the emitted light changes its phase ratio and emits light. This high organic light emitting display device can be implemented.

Claims (14)

First and second substrates, A light emitting element formed between the first and second substrates and emitting light; A retardation plate disposed on the substrate in a path through which light emitted from the light emitting device propagates and changing a phase of incident light; A first polarizer disposed on the retardation plate and reflecting light in a specific polarization direction, A second polarizer disposed on the first polarizer and transmitting light in a polarization direction opposite to the specific polarization direction, and An organic light emitting display device comprising an anti-reflection film disposed on the second polarizer. The organic light emitting diode display of claim 1, wherein the light emitting device comprises first and second electrodes and an organic thin film layer formed between the first and second electrodes. The organic light emitting diode display of claim 2, wherein the organic thin film layer comprises a hole transport layer, an organic emission layer, and an electron transport layer. The organic light emitting diode display of claim 1, wherein the retardation plate is configured to change a phase of the incident light by 45 °. The organic light emitting diode display of claim 1, wherein the first polarizer comprises a reflective polarizer. The organic light emitting diode display of claim 5, wherein the reflective polarizer is a wire grid. The organic light emitting diode display of claim 1, wherein the second polarizer comprises an iodine-based absorption type polarizing plate. delete The organic light emitting display device of claim 1, wherein the anti-reflection film is formed of an anti-glare film or an anti-reflection film. Board, A light emitting device formed on the substrate and emitting light; A protective film formed on the entire upper surface including the light emitting element, A phase difference plate formed on the passivation layer and changing a phase of incident light; A first polarizer disposed on the retardation plate and reflecting light in a specific polarization direction, And a second polarizer disposed on the first polarizer and configured to transmit light in a polarization direction opposite to the specific polarization direction. The organic light emitting diode display of claim 10, wherein the retardation plate is configured to change a phase of the incident light by 45 °. The organic light emitting diode display of claim 10, wherein the first polarizer comprises a reflective polarizer. The organic light emitting diode display of claim 12, wherein the reflective polarizer is a wire grid. The organic light emitting diode display of claim 10, wherein the second polarizer comprises an iodine-based absorption polarizing plate.

Images